Dr. Ulrik Hinxler Kesmodell, an expert at the Fertility Clinic at Aarhus University Hospital in Denmark, and his colleagues conducted a follow-up study on 3,959 cases of in vitro fertilization. The researchers collected information on the coffee drinking volume of the participating patients and analyzed it based on factors such as age, smoking status, drinking status, and weight. The results found that female participants who drank at least 5 cups of coffee a day had a 50% lower chance of pregnancy, but women who drank less than 5 cups of coffee a day did not experience this "side effect."

Early research on the link between coffee and fertility has been mixed. Some studies have found that excessive caffeine intake can cause miscarriage, while others have found the opposite. Research in recent years generally believes that women who drink too much tea or coffee every day, and their husbands who drink too much, etc., will greatly reduce a woman's chance of pregnancy.

For this reason, British expert Euan Paul reminds pregnant women and women preparing for pregnancy that their daily caffeine intake should be controlled within 200 mg (within 2 cups).